MME reselection method and MME

ABSTRACT

An MME reselection method and an MME are provided, so that UE can use a correct MME in time to execute an access request procedure. The method includes: receiving an access request message sent by user equipment UE, where the access request message carries identity information of the UE ( 801 ); determining, according to the identity information of the UE, a type of an MME that the UE needs to access ( 802 ); reselecting a second MME according to the type of the MME that the UE needs to access ( 803 ); and forwarding the access request message to the second MME, so that the second MME executes an access request procedure of the UE ( 804 ). The embodiments of the present invention is applicable to the field of communications technologies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2014/080113 filed on Jun. 17, 2014, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present invention relate to the field ofcommunications technologies, and in particular, to an MME reselectionmethod and an MME.

BACKGROUND

For authorized user equipment (UE for short) that has signed a networkaccess protocol with an operator, to normally use a subscribed serviceover a network, each time the UE is powered on, the UE needs tocomplete, on the network of the operator, a procedure of registeringwith and attaching to the network; or after a preset time since the UEcompletely leaves coverage of the network, the UE needs to completeagain, on the network of the operator, a procedure of registering withand attaching to the network; or when entering from an area of thenetwork of the operator to another area, the UE needs to perform arouting area update procedure.

Currently, because on-net UEs subscribe to different services and havedifferent charging standards, an operator expects to classify mobilitymanagement entities (MME for short), and different MMEs process accessrequests of UEs that subscribe to different services. In this way, userssubscribing to different services are logically managed separately,which can improve management efficiency of a communications operator.For example, for all user equipments that subscribe to an M2M service, agroup of dedicated MMEs are used for management; for all user equipmentsthat do not subscribe to an M2M service, another group of MMEs are usedfor management.

However, in a Long Term Evolution (LTE for short) network, when UEexecutes an attach procedure or a routing area update procedure, anevolved node eNodeB selects an MME for the UE by depending on only anetwork topology. In this way, it is possible that the eNodeB selects awrong MME for the UE. Therefore, in a case in which MMEs are classifiedinto multiple classes and provide services to UEs subscribing toservices of different types, how to select an MME is a problem thaturgently needs to be resolved.

SUMMARY

Embodiments of the present invention provide an MME reselection methodand an MME, so that UE can use a correct MME in time to execute anaccess request procedure.

To achieve the foregoing objective, the following technical solutionsare used in the embodiments of the present invention:

According to a first aspect, a first mobility management entity MME isprovided, where the first MME includes:

a receiving unit, configured to receive an access request message sentby user equipment UE, where the access request message carries identityinformation of the UE;

a determining unit, configured to determine, according to the identityinformation of the UE, a type of an MME that the UE needs to access;

a reselection unit, configured to reselect a second MME according to thetype of the MME that the UE needs to access; and

a sending unit, configured to forward the access request message to thesecond MME, so that the second MME executes an access request procedureof the UE.

With reference to the first aspect, in a first possible implementationmanner,

the receiving unit is further configured to receive an interactionmessage that is generated between the UE and the second MME duringexecution of the access request procedure; and

the sending unit is further configured to forward the interactionmessage that is generated between the UE and the second MME duringexecution of the access request procedure.

With reference to the first aspect or the first possible implementationmanner of the first aspect, in a second possible implementation manner,the determining unit is specifically configured to:

determine, according to the identity information of the UE andpreconfiguration indication information, the type of the MME that the UEneeds to access, where the preconfiguration indication informationincludes information about a correspondence between the identityinformation of the UE and the type of the MME that the UE needs toaccess.

With reference to the first aspect or the first possible implementationmanner of the first aspect, in a third possible implementation manner,the determining unit is specifically configured to:

obtain subscription data of the UE from a home subscriber server HSSaccording to the identity information of the UE, where the subscriptiondata includes information about the type of the MME that the UE needs toaccess; and

determine, according to the subscription data, the type of the MME thatthe UE needs to access.

With reference to the first aspect or the first possible implementationmanner of the first aspect, in a fourth possible implementation manner,the determining unit is specifically configured to:

obtain, according to the identity information of the UE, mobilitymanagement context information of the UE from an original MME accessedby the UE, where the mobility management context information includesinformation about the type of the MME that the UE needs to access; and

determine, according to the mobility management context information, thetype of the MME that the UE needs to access.

According to the fourth possible implementation manner of the firstaspect, in a fifth possible implementation manner, the sending unit isspecifically configured to forward the access request message and themobility management context information of the UE to the second MME, sothat the second MME executes the access request procedure of the UEaccording to the access request message and the mobility managementcontext information of the UE.

According to a second aspect, a second mobility management entity MME isprovided, where the second MME includes:

a receiving unit, configured to receive an access request message thatis sent by user equipment UE and that is forwarded by a first MME, wherethe access request message includes an identity of the UE; and

a processing unit, configured to execute an access request procedure ofthe UE according to the access request message.

With reference to the second aspect, in a first possible implementationmanner, the second MME further includes:

a sending unit, configured to send an interaction message to the UE byusing the first MME when the processing unit executes the access requestprocedure of the UE according to the access request message, where

the receiving unit is specifically configured to: when the processingunit executes the access request procedure of the UE according to theaccess request message, receive, by using the first MME, an interactionmessage sent by the UE.

With reference to the second aspect or the first possible implementationmanner of the second aspect, in a second possible implementation manner,

the receiving unit is further configured to receive mobility managementcontext information of the UE forwarded by the first MME; and

the processing unit is specifically configured to execute the accessrequest procedure of the UE according to the access request message andthe mobility management context information of the UE.

With reference to the second aspect or the first possible implementationmanner of the second aspect, in a third possible implementation manner,

the sending unit is further configured to send a mobility managementcontext request message to an original MME of the UE according to theidentity of the UE carried in the access request message;

the receiving unit is further configured to receive a mobilitymanagement context response message sent by the original MME of the UE,where the mobility management context response message carries mobilitymanagement context information of the UE; and

the processing unit is specifically configured to execute the accessrequest procedure of the UE according to the access request message andthe mobility management context information of the UE.

According to a third aspect, a first mobility management entity MME isprovided, where the first MME includes:

a receiver, configured to receive an access request message sent by userequipment UE, where the access request message carries identityinformation of the UE;

a processor, configured to: determine, according to the identityinformation of the UE, a type of an MME that the UE needs to access; andreselect a second MME according to the type of the MME that the UE needsto access; and

a transmitter, configured to forward the access request message to thesecond MME, so that the second MME executes an access request procedureof the UE.

With reference to the third aspect, in a first possible implementationmanner,

the receiver is further configured to receive an interaction messagethat is generated between the UE and the second MME during execution ofthe access request procedure; and

the transmitter is further configured to forward the interaction messagethat is generated between the UE and the second MME during execution ofthe access request procedure.

With reference to the third aspect or the first possible implementationmanner of the third aspect, in a second possible implementation manner,the processor is specifically configured to:

determine, according to the identity information of the UE andpreconfiguration indication information, the type of the MME that the UEneeds to access, where the preconfiguration indication informationincludes information about a correspondence between the identityinformation of the UE and the type of the MME that the UE needs toaccess.

With reference to the third aspect or the first possible implementationmanner of the third aspect, in a third possible implementation manner,the processor is specifically configured to:

obtain subscription data of the UE from a home subscriber server HSSaccording to the identity information of the UE, where the subscriptiondata includes information about the type of the MME that the UE needs toaccess; and

determine, according to the subscription data, the type of the MME thatthe UE needs to access.

With reference to the third aspect or the first possible implementationmanner of the third aspect, in a fourth possible implementation manner,the processor is specifically configured to:

obtain, according to the identity information of the UE, mobilitymanagement context information of the UE from an original MME accessedby the UE, where the mobility management context information includesinformation about the type of the MME that the UE needs to access; and

determine, according to the mobility management context information, thetype of the MME that the UE needs to access.

According to the fourth possible implementation manner of the thirdaspect, in a fifth possible implementation manner, the transmitter isspecifically configured to forward the access request message and themobility management context information of the UE to the second MME, sothat the second MME executes the access request procedure of the UEaccording to the access request message and the mobility managementcontext information of the UE.

According to a fourth aspect, a second mobility management entity MME isprovided, where the second MME includes:

a receiver, configured to receive an access request message that is sentby user equipment UE and that is forwarded by a first MME, where theaccess request message includes an identity of the UE; and

a processor, configured to execute an access request procedure of the UEaccording to the access request message.

With reference to the fourth aspect, in a first possible implementationmanner, the second MME further includes:

a transmitter, configured to send an interaction message to the UE byusing the first MME when the processor executes the access requestprocedure of the UE according to the access request message, where

the receiver is specifically configured to: when the processor executesthe access request procedure of the UE according to the access requestmessage, receive, by using the first MME, an interaction message sent bythe UE.

With reference to the fourth aspect or the first possible implementationmanner of the fourth aspect, in a second possible implementation manner,

the receiver is further configured to receive mobility managementcontext information of the UE forwarded by the first MME; and

the processor is specifically configured to execute the access requestprocedure of the UE according to the access request message and themobility management context information of the UE.

With reference to the fourth aspect or the first possible implementationmanner of the fourth aspect, in a third possible implementation manner,

the transmitter is further configured to send a mobility managementcontext request message to an original MME of the UE according to theidentity of the UE carried in the access request message;

the receiver is further configured to receive a mobility managementcontext response message sent by the original MME of the UE, where themobility management context response message carries mobility managementcontext information of the UE; and

the processor is specifically configured to execute the access requestprocedure of the UE according to the access request message and themobility management context information of the UE.

According to a fifth aspect, a mobility management entity MMEreselection method is provided, where the method includes:

receiving an access request message sent by user equipment UE, where theaccess request message carries identity information of the UE;

determining, according to the identity information of the UE, a type ofan MME that the UE needs to access;

reselecting a second MME according to the type of the MME that the UEneeds to access; and

forwarding the access request message to the second MME, so that thesecond MME executes an access request procedure of the UE.

With reference to the fifth aspect, in a first possible implementationmanner, after the forwarding the access request message to the secondMME, so that the second MME executes an access request procedure of theUE, the method further includes:

receiving an interaction message that is generated between the UE andthe second MME during execution of the access request procedure; and

forwarding the interaction message that is generated between the UE andthe second MME during execution of the access request procedure.

With reference to the fifth aspect or the first possible implementationmanner of the fifth aspect, in a second possible implementation manner,the determining, according to the identity information of the UE, a typeof an MME that the UE needs to access specifically includes:

determining, according to the identity information of the UE andpreconfiguration indication information, the type of the MME that the UEneeds to access, where the preconfiguration indication informationincludes information about a correspondence between the identityinformation of the UE and the type of the MME that the UE needs toaccess.

With reference to the fifth aspect or the first possible implementationmanner of the fifth aspect, in a third possible implementation manner,the determining, according to the identity information of the UE, a typeof an MME that the UE needs to access specifically includes:

obtaining subscription data of the UE from a home subscriber server HSSaccording to the identity information of the UE, where the subscriptiondata includes information about the type of the MME that the UE needs toaccess; and

determining, according to the subscription data, the type of the MMEthat the UE needs to access.

With reference to the fifth aspect or the first possible implementationmanner of the fifth aspect, in a fourth possible implementation manner,the determining, according to the identity information of the UE, a typeof an MME that the UE needs to access specifically includes:

obtaining, according to the identity information of the UE, mobilitymanagement context information of the UE from an original MME accessedby the UE, where the mobility management context information includesinformation about the type of the MME that the UE needs to access; and

determining, according to the mobility management context information,the type of the MME that the UE needs to access.

According to the fourth possible implementation manner of the fifthaspect, in a fifth possible implementation manner, after the forwardingthe access request message to the second MME, the method furtherincludes:

forwarding the mobility management context information of the UE to thesecond MME.

According to a sixth aspect, a mobility management entity MMEreselection method is provided, where the method includes:

receiving an access request message that is sent by user equipment UEand that is forwarded by a first MME, where the access request messageincludes an identity of the UE; and

executing an access request procedure of the UE according to the accessrequest message.

With reference to the sixth aspect, in a first possible implementationmanner, the executing an access request procedure of the UE according tothe access request message specifically includes:

sending an interaction message to the UE by using the first MME, andreceiving, by using the first MME, an interaction message sent by theUE.

With reference to the sixth aspect or the first possible implementationmanner of the sixth aspect, in a second possible implementation manner,before the executing an access request procedure of the UE according tothe access request message, the method further includes:

receiving mobility management context information of the UE forwarded bythe first MME; and

the executing an access request procedure of the UE according to theaccess request message specifically includes:

executing the access request procedure of the UE according to the accessrequest message and the mobility management context information of theUE.

With reference to the sixth aspect or the first possible implementationmanner of the sixth aspect, in a third possible implementation manner,after the receiving an access request message that is sent by userequipment UE and that is forwarded by a first MME, the method furtherincludes:

sending a mobility management context request message to an original MMEof the UE according to the identity of the UE carried in the accessrequest message;

receiving a mobility management context response message sent by theoriginal MME of the UE, where the mobility management context responsemessage carries mobility management context information of the UE; and

the executing an access request procedure of the UE according to theaccess request message specifically includes:

executing the access request procedure of the UE according to the accessrequest message and the mobility management context information of theUE.

By means of the MME reselection method and the MME that are provided inthe embodiments of the present invention, based on the foregoingtechnical solutions, a first MME may reselect, for UE, an MME that theUE needs to access, that is, a second MME, and forward an access requestmessage of the UE to the second MME, and the second MME may execute anaccess request procedure of the UE according to the access requestmessage of the UE forwarded by the first MME, so that the UE can use acorrect MME in time to execute the access request procedure.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention or in the prior art more clearly, the following brieflydescribes the accompanying drawings required for describing theembodiments or the prior art. Apparently, the accompanying drawings inthe following description show merely some embodiments of the presentinvention, and persons of ordinary skill in the art may still deriveother drawings from these accompanying drawings without creativeefforts.

FIG. 1 is an architectural diagram of a wireless network of an evolvedpacket system EPS in LTE;

FIG. 2 is an schematic interaction diagram of an attach procedure inLTE;

FIG. 3 is an schematic interaction diagram of a routing area updateprocedure in LTE;

FIG. 4 is a schematic structural composition diagram of a first MMEaccording to an embodiment of the present invention;

FIG. 5 is a schematic structural composition diagram of a second MMEaccording to an embodiment of the present invention;

FIG. 5a is a schematic structural composition diagram of another secondMME according to an embodiment of the present invention;

FIG. 6 is a schematic structural composition diagram of a first MMEaccording to an embodiment of the present invention;

FIG. 7 is a schematic structural composition diagram of a second MMEaccording to an embodiment of the present invention;

FIG. 7a is a schematic structural composition diagram of another secondMME according to an embodiment of the present invention;

FIG. 8 is a schematic flowchart 1 of an MME reselection method accordingto an embodiment of the present invention;

FIG. 9 is a schematic flowchart 2 of an MME reselection method accordingto an embodiment of the present invention;

FIG. 10 is a schematic interaction diagram 1 of executing an attachprocedure in an MME reselection method according to an embodiment of thepresent invention;

FIG. 11 is a schematic interaction diagram 2 of executing an attachprocedure in an MME reselection method according to an embodiment of thepresent invention;

FIG. 12 is a schematic interaction diagram 1 of executing a routing areaupdate procedure in an MME reselection method according to an embodimentof the present invention; and

FIG. 13 is a schematic interaction diagram 2 of executing a routing areaupdate procedure in an MME reselection method according to an embodimentof the present invention.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, thedescribed embodiments are merely some but not all of the embodiments ofthe present invention. All other embodiments obtained by persons ofordinary skill in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

In addition, to briefly describe the following embodiments, severalrelated definitions are provided below, and details are as follows:

A first MME: an MME selected by an eNodeB for UE according to a networktopology.

A second MME: an MME that is determined by a first MME according toidentity information of the UE and that the UE needs to access, wherethe MME that the UE needs to access is referred to as a second MME.

An original MME: an MME that executes an attach procedure of UE or anMME that executes a previous routing area update procedure before the UEinitiates a current routing area update request.

Specifically, before the current routing area update request isinitiated, if a previously completed access request initiated by the UEis an attach request, the original MME herein refers to an MME thatexecutes an attach procedure of the UE; before the current routing areaupdate request is initiated, if a previously completed access requestinitiated by the UE is a routing area update request, the original MMEherein refers to an MME that executes a previous routing area updateprocedure.

It should be noted that the foregoing definitions are applicable to thefollowing embodiments, and are described herein together; details arenot described below again.

LTE is informally referred to as 3.9G, has a 100 Mbps data downloadingcapability, and is considered as a mainstream technology evolving from3G to 4G. An evolved packet core (EPC for short) is a set of solutionsthat helps operators to provide advanced mobile broadband services byusing an LTE technology. A core network in LTE evolves to the EPC, and acombination of the EPC and an evolved universal terrestrial radio accessnetwork (EUTRAN for short) is referred to as an evolved packet system(EPS for short).

A wireless network architecture of the EPS is shown in FIG. 1, andincludes network entities, such as UE, an EUTRAN, an MME, a servinggateway (S-GW for short), a packet data network gateway (P-GW forshort), an HSS, a serving general packet radio service support node(SGSN for short), a policy and charging rules function (PCRF for short)unit, and a server by using which an operator can provide an IP service.

Specifically, functions of main network entities are as follows:

The EUTRAN is a network including multiple eNodeBs, and implements awireless physical layer function, resource scheduling and radio resourcemanagement, radio access control, and a mobility management function.

The eNodeB is connected to an S-GW by using a user plane interface S1-U,and is configured to transport user data; and is connected to an MME byusing a control plane interface S1-MME, and implement, by using an S1-APprotocol, functions of controlling a radio access bearer and the like.

The MME is responsible for all control plane functions in user sessionmanagement, including NAS signaling and security setting, tracking arealist management, selection of a P-GW and an S-GW, and the like.

The S-GW is responsible for transmitting and forwarding data of UE androuting switching, and is used as a local mobility anchoring point whenthe UE performs switching between eNodeBs (for each UE, only one S-GWserves the UE at each moment).

The P-GW is used as an anchoring point of a PDN connection, and isresponsible for allocating an IP address of UE, filtering data packetsof UE, rate control, generating charging information, and the like.

Specifically, UE accesses an EPS network and establishes a packet datanetwork (PDN) connection by using an attach procedure or a routing areaupdate procedure. In this process, the P-GW allocates an IP address tothe user equipment, and the UE implements data transmission with anexternal network by using the IP address.

First, for ease of understanding the present invention, an attachprocedure and a routing area update procedure of UE in the prior art arebriefly described below.

Specifically, an implementation process of the attach procedure of theUE is shown in FIG. 2, and details are as follows:

201: UE sends an attach request message to an eNodeB.

The attach request message includes information such as an IMSI, a corenetwork capability of the UE, a discontinuous reception parameterspecified by the UE, an encryption option transmission mark, an attachtype, a NAS sequence number, and NAS-media access control.

202: The eNodeB forwards, to a first MME, the attach request messagesent by the UE.

The attach request message further includes user location information.

203 a: The first MME and an HSS authenticate the UE.

203 b: The first MME and the UE perform security setting on a non-accessstratum (NAS for short) message.

Specifically, the first MME and the UE perform security setting, such asintegrity protection, an encryption manner, or key information, on theNAS message.

204: The first MME exchanges a location update request message and alocation update request acknowledgement message with the HSS.

Specifically, the first MME sends the location update request message tothe HSS. The HSS updates stored information about a location of an MMEon which the UE is located, and after the update is completed, returnsthe location update request acknowledgement message to the first MME,and returns subscription information of the UE to the first MME.

205: The first MME sends a create session request message to an S-GW.

Specifically, the first MME selects an S-GW and a P-GW for the UEaccording to the subscription information of the UE, and sends thecreate session request message to the selected S-GW.

The create session request message includes an IMSI of the UE, anaddress of a P-GW needing to be accessed, a type of an accesstechnology, user location information, an identifier of an EPS bearer,and the like.

206: The S-GW is connected to a P-GW and sends the create sessionrequest message to the P-GW.

Specifically, the S-GW creates default bearer context information, andconnects to and sends the create session request message to the P-GWaccording to the address, which is included in the session requestmessage, of the P-GW needing to the accessed.

The default bearer context information includes allocation of a userplane tunnel endpoint identifier (TEID for short) to a default bearer,and the like.

The create session message includes the IMSI, a user plane address ofthe S-GW, a user plane TEID of the S-GW, the type of the accesstechnology, the user location information, the identifier of the EPSbearer, and the like.

207: The P-GW returns a create session response message to the S-GW.

Specifically, the P-GW creates default bearer context information,generates a charging identifier of a default bearer, and returns thecreate session response message to the S-GW.

The default bearer context information includes allocation of a userplane TEID to the default bearer.

The create session response message includes information such as a userplane address of the P-GW, a user plane TEID of the P-GW, the identifierof the EPS bearer, and an IP address allocated to the UE. Since thisstep, the P-GW starts to forward initial downlink data. Since this step,the S-GW starts to buffer downlink data received from the P-GW.

208: The S-GW returns the create session response message to the firstMME.

The create session response message includes the IP address allocated tothe UE, the user plane address of the S-GW, the user plane TEID of theS-GW, quality of service (QoS for short) of the EPS bearer, theidentifier of the EPS bearer, and the like.

209: The first MME sends an initial context setup request message theeNodeB.

The initial context setup request message includes information such asthe QoS of the EPS bearer, the identifier of the EPS bearer, the userplane address of the S-GW, and the user plane TEID of the S-GW. Theinitial context setup request message further includes content of anattach accept message that is sent by the first MME to the UE by usingthe eNodeB, and the content of the attach accept message includesinformation such as the IP address allocated to the UE, the identifierof the EPS bearer, and the QoS of the EPS bearer.

210: The eNodeB sends a radio resource control protocol connectionreconfiguration message to the UE.

The radio resource control protocol connection reconfiguration messagefurther includes the content of the attach accept message that is sentby the first MME to the UE by using the eNodeB, and the content of theattach accept message includes information such as the IP addressallocated to the UE, the identifier of the EPS bearer, and the QoS ofthe EPS bearer.

211: The UE sends a radio resource control protocol connectionreconfiguration complete message to the eNodeB.

212: The eNodeB sends an initial context setup response message thefirst MME.

The initial context setup response message includes a TEID allocated bythe eNodeB to a user plane, a user plane address of the eNodeB, and thelike.

213: The UE sends a direct transmission message to the eNodeB.

The direct transmission message includes content of an attach completemessage that is sent by the UE to the first MME by using the eNodeB.

214: The eNodeB forwards an attach complete message to the first MME.

215: The first MME sends a bearer update request message to the S-GW.

Specifically, after the first MME receives the initial context setupresponse message and the attach complete message, the first MME sendsthe bearer update request message to the S-GW.

The bearer update request message includes the TEID allocated by theeNodeB to the user plane and the user plane address of the eNodeB.

216: The S-GW sends a bearer update response message to the first MME,and starts to send, to the eNodeB, a downlink data packet that isbuffered starting from step 207.

An implementation process of the routing area update procedure of the UEis shown in FIG. 3, and details are as follows:

301: UE sends a routing area update request message to an eNodeB.

The routing area update request message includes a globally uniquetemporary identity (GUTI for short) of the UE, where the identity isallocated by an original MME, the GUTI includes a globally unique MMEidentifier (GUMMEI for short), and the GUMMEI is allocated, to the UE,by an MME that executes an attach procedure of the UE or an MME thatexecutes a previous routing area update procedure.

302: The eNodeB forwards the routing area update request message to afirst MME.

Specifically, the eNodeB selects one MME, that is, the first MME, forthe UE according to a network topology, and forwards a routing areaupdate request of the UE to the first MME.

303: The first MME sends a mobility management context request messageto an original MME.

Specifically, the first MME learns, according to information about theGUMMEI included in the GUTI, an address of the original MME at which amobility management context of the UE is located, and sends the mobilitymanagement context request message to the original MME.

The mobility management context request message includes the GUTI of theUE.

304: The original MME returns a mobility management context responsemessage to the first MME.

Specifically, the original MME determines a mobility management contextof the UE according to the GUTI of the UE, and returns the mobilitymanagement context, which is included in the mobility management contextresponse message, of the UE to the first MME.

305 a: The first MME and an HSS authenticate the UE.

305 b: The first MME and the UE perform security setting on a NASmessage.

Specifically, the first MME and the UE perform security setting, such asintegrity protection, an encryption manner, or key information, on theNAS message.

It should be noted that whether this step exists depends on 304.

If a mobility management context that is returned by the original MME tothe first MME in 304 includes a security context of the original MME andthe UE, this step is omitted, and the first MME and the UE do not needto perform security setting on the NAS message.

If a mobility management context that is returned by the original MME tothe first MME in 304 does not include a security context of the originalMME and the UE, the first MME and the UE need to perform securitysetting on the NAS message in this step.

306: The first MME sends a context acknowledgement message to theoriginal MME.

The context message includes an S-GW change indication that indicateswhether the S-GW changes in the routing area update procedure, so thatthe original MME decides whether to delete a stored user context of anoriginal S-GW, where the original S-GW is an S-GW that is selected bythe original MME for the UE.

307: The first MME initiates a bearer update request message to theS-GW.

Specifically, the first MME initiates the bearer update request messageto the S-GW, and provides location information and the like of thecurrent UE.

308: The S-GW sends a bearer update request message to a P-GW.

309: The P-GW returns a bearer update response message to the S-GW.

310: The S-GW sends the bearer update response message to the first MME.

311: The first MME sends a location update request message to the HSS.

Specifically, the first MME sends the location update request message tothe HSS, and the HSS updates stored location information of the UE,where the HSS updates information about a location at which the UE isserved by the original MME to information about a location at which theUE is served by the first MME.

312: The HSS exchanges a location deletion request message and alocation deletion request acknowledgement message with the original MME.

Specifically, the HSS sends the location deletion request message to theoriginal MME, and the original MME removes a user mobility managementcontext, and returns the location deletion acknowledgement message tothe HSS.

313: The HSS returns a location update request acknowledgement messageto the first MME.

Specifically, after updating information about a location of the firstMME on which the UE is located, the HSS returns the location updaterequest acknowledgement message to the first MME, and sends usersubscription data to the first MME.

314: The first MME sends a routing area update accept message to theeNodeB.

The routing area update accept message includes a GUTI that isreallocated by the first MME to the UE.

315: The eNodeB forwards the routing area update accept message to theUE.

In specific implementation processes of the foregoing procedures, whenUE executes an attach procedure or a routing area update procedure, aneNodeB selects an MME for the UE depending on only a network topology;therefore, it is possible that the eNodeB selects a wrong MME for theUE.

In view of this, an embodiment of the present invention provides a firstMME. As shown in FIG. 4, the MME includes: a receiving unit 401, adetermining unit 402, a reselection unit 403, and a sending unit 404.

The receiving unit 401 is configured to receive an access requestmessage sent by user equipment UE, where the access request messagecarries identity information of the UE.

The determining unit 402 is configured to determine, according to theidentity information of the UE, a type of an MME that the UE needs toaccess.

The reselection unit 403 is configured to reselect a second MMEaccording to the type of the MME that the UE needs to access.

The sending unit 404 is configured to forward the access request messageto the second MME, so that the second MME executes an access requestprocedure of the UE.

Optionally, the receiving unit 401 is further configured to receive aninteraction message that is generated between the UE and the second MMEduring execution of the access request procedure; and

optionally, the sending unit 402 is further configured to forward theinteraction message that is generated between the UE and the second MMEduring execution of the access request procedure.

The determining unit 402 is specifically configured to:

determine, according to the identity information of the UE andpreconfiguration indication information, the type of the MME that the UEneeds to access, where the preconfiguration indication informationincludes information about a correspondence between the identityinformation of the UE and the type of the MME that the UE needs toaccess.

Optionally, the determining unit 402 is further specifically configuredto: obtain subscription data of the UE from a home subscriber server HSSaccording to the identity information of the UE, where the subscriptiondata includes information about the type of the MME that the UE needs toaccess; and determine, according to the subscription data, the type ofthe MME that the UE needs to access.

Optionally, the determining unit 402 is further specifically configuredto: obtain, according to the identity information of the UE, mobilitymanagement context information of the UE from an original MME accessedby the UE, where the mobility management context information includesinformation about the type of the MME that the UE needs to access; anddetermine, according to the mobility management context information, thetype of the MME that the UE needs to access.

Optionally, the sending unit 404 is specifically configured to forwardthe access request message and the mobility management contextinformation of the UE to the second MME, so that the second MME executesthe access request procedure of the UE according to the access requestmessage and the mobility management context information of the UE.

This embodiment of the present invention provides a first MME. Based onthe foregoing technical solution, the first MME may reselect, for UE, anMME that the UE needs to access, that is, a second MME, and forward anaccess request message of the UE to the second MME, so that the UE canuse a correct MME in time to execute an access request procedure.

Based on the first MME provided in the foregoing embodiment, anembodiment of the present invention further provides a second MME. Asshown in FIG. 5, the MME includes: a receiving unit 501 and a processingunit 502.

The receiving unit 501 is configured to receive an access requestmessage that is sent by user equipment UE and that is forwarded by thefirst MME, where the access request message includes an identity of theUE; and

the processing unit 502 is configured to execute an access requestprocedure of the UE according to the access request message.

Optionally, as shown in FIG. 5a , the second MME further includes:

a sending unit 503, configured to send an interaction message to the UEby using the first MME when the processing unit 502 executes the accessrequest procedure of the UE according to the access request message,where

the receiving unit 501 is specifically configured to: when theprocessing unit 502 executes the access request procedure of the UEaccording to the access request message, receive, by using the firstMME, an interaction message sent by the UE.

Optionally, the receiving unit 501 is further configured to receivemobility management context information of the UE forwarded by the firstMME; and

the processing unit 502 is specifically configured to execute the accessrequest procedure of the UE according to the access request message andthe mobility management context information of the UE.

Optionally, the sending unit 503 is further configured to send amobility management context request message to an original MME of the UEaccording to the identity of the UE carried in the access requestmessage;

the receiving unit 501 is further configured to receive a mobilitymanagement context response message sent by the original MME of the UE,where the mobility management context response message carries mobilitymanagement context information of the UE; and

the processing unit 502 is specifically configured to execute the accessrequest procedure of the UE according to the access request message andthe mobility management context information of the UE.

This embodiment of the present invention provides a second MME. Based onthe foregoing technical solution, the second MME may execute an accessrequest procedure of UE according to an access request message of the UEforwarded by a first MME, so that the UE can use a correct MME in timeto execute the access request procedure.

Based on the first MME provided in the foregoing embodiment, anembodiment of the present invention further provides a first MME. Asshown in FIG. 6, the first MME includes: a receiver 601, a processor602, a transmitter 603, a memory 604, and a first communications bus 605that is configured to implement a connection and communication betweenthese apparatuses.

The processor 602 may be a central processing unit (CPU for short) or anapplication-specific integrated circuit (ASIC for short), or isconfigured as one or more integrated circuits that implement thisembodiment of the present invention.

The processor 602 is configured to execute executable program code, forexample, a computer program, stored in the memory 604, to run a programcorresponding to the executable code.

The memory 604 is configured to store the executable program code, wherethe program code includes a computer operation instruction. The memory604 may include a high-speed RAM memory, and may further include anon-volatile memory, such as at least one magnetic disk storage.

The first communications bus 605 may be an Industry StandardArchitecture (ISA for short) bus, a peripheral component interconnect(PCI for short) bus, an Extended Industry Standard Architecture (EISAfor short) bus, or the like. The bus 605 may be classified into anaddress bus, a data bus, a control bus, and the like. For ease ofrepresentation, the bus in FIG. 6 is represented by using only one boldline, but it does not indicate that there is only one bus or only onetype of bus.

Specifically, the receiver 601 is configured to receive an accessrequest message sent by user equipment UE, where the access requestmessage carries identity information of the UE;

the processor 602 is configured to: determine, according to the identityinformation of the UE, a type of an MME that the UE needs to access; andreselect a second MME according to the type of the MME that the UE needsto access; and

the transmitter 603 is configured to forward the access request messageto the second MME, so that the second MME executes an access requestprocedure of the UE.

Optionally, the receiver 601 is further configured to receive aninteraction message that is generated between the UE and the second MMEduring execution of the access request procedure; and

the transmitter 603 is further configured to forward the interactionmessage that is generated between the UE and the second MME duringexecution of the access request procedure.

The processor 602 is specifically configured to determine, according tothe identity information of the UE and preconfiguration indicationinformation, the type of the MME that the UE needs to access, where thepreconfiguration indication information includes information about acorrespondence between the identity information of the UE and the typeof the MME that the UE needs to access.

Optionally, the processor 602 is further specifically configured to:obtain subscription data of the UE from a home subscriber server HSSaccording to the identity information of the UE, where the subscriptiondata includes information about the type of the MME that the UE needs toaccess; and determine, according to the subscription data, the type ofthe MME that the UE needs to access.

Optionally, the processor 602 is further specifically configured to:obtain, according to the identity information of the UE, mobilitymanagement context information of the UE from an original MME accessedby the UE, where the mobility management context information includesinformation about the type of the MME that the UE needs to access; anddetermine, according to the mobility management context information, thetype of the MME that the UE needs to access.

Optionally, the transmitter 603 is specifically configured to forwardthe access request message and the mobility management contextinformation of the UE to the second MME, so that the second MME executesthe access request procedure of the UE according to the access requestmessage and the mobility management context information of the UE.

This embodiment of the present invention provides a first MME. Based onthe foregoing technical solution, the first MME may reselect, for UE, anMME that the UE needs to access, that is, a second MME, and forward anaccess request message of the UE to the second MME, so that the UE canuse a correct MME in time to execute an access request procedure.

Based on the second MME provided in the foregoing embodiment, anembodiment of the present invention further provides a second MME. Asshown in FIG. 7, the second MME includes: a receiver 701, a processor702, a memory 703, and a first communications bus 704 that is configuredto implement a connection and communication between these apparatuses.

The processor 702 may be a central processing unit (CPU for short) or anapplication-specific integrated circuit (ASIC for short), or isconfigured as one or more integrated circuits that implement theembodiment of the present invention.

The processor 702 is configured to execute executable program code, forexample, a computer program, stored in the memory 703, to run a programcorresponding to the executable code.

The memory 703 is configured to store executable program code, where theprogram code includes a computer operation instruction. The memory 703may include a high-speed RAM memory, and may further include anon-volatile memory, such as at least one magnetic disk memory.

The first communications bus 704 may be an Industry StandardArchitecture (ISA for short) bus, a peripheral component interconnect(PCI for short) bus, an Extended Industry Standard Architecture (EISAfor short) bus, or the like. The bus 704 may be classified into anaddress bus, a data bus, a control bus, and the like. For ease ofrepresentation, the bus in FIG. 7 is represented by using only one boldline, but it does not indicate that there is only one bus or only onetype of bus.

Specifically, the receiver 701 is configured to receive an accessrequest message that is sent by user equipment UE and that is forwardedby first MME, where the access request message includes an identity ofthe UE; and

the processor 702 is configured to execute an access request procedureof the UE according to the access request message.

Optionally, as shown in FIG. 7a , the second MME further includes:

a transmitter 705, configured to send an interaction message to the UEby using the first MME when the processor 702 executes the accessrequest procedure of the UE according to the access request message,where

the receiver 701 is specifically configured to: when the processor 702executes the access request procedure of the UE according to the accessrequest message, receive, by using the first MME, an interaction messagesent by the UE.

Optionally, the receiver 701 is further configured to receive mobilitymanagement context information of the UE forwarded by the first MME; and

the processor 702 is specifically configured to execute the accessrequest procedure of the UE according to the access request message andthe mobility management context information of the UE.

Optionally, the transmitter 705 is further configured to send a mobilitymanagement context request message to an original MME of the UEaccording to the identity of the UE carried in the access requestmessage;

the receiver 701 is further configured to receive a mobility managementcontext response message sent by the original MME of the UE, where themobility management context response message carries mobility managementcontext information of the UE; and

the processor 702 is specifically configured to execute the accessrequest procedure of the UE according to the access request message andthe mobility management context information of the UE.

This embodiment of the present invention provides a second MME. Based onthe foregoing technical solution, the second MME may execute an accessrequest procedure of UE according to an access request message of the UEforwarded by a first MME, so that the UE can use a correct MME in timeto execute the access request procedure.

Based on the first MME provided in the foregoing embodiment, anembodiment of the present invention provides an MME reselection method.The method is executed by the first MME. As shown in FIG. 8, the methodincludes:

801: Receive an access request message sent by UE, where the accessrequest message carries identity information of the UE.

The UE selects, according to a system broadcast message of an eNodeB, anappropriate cell to camp on, and initiates an access request procedureto the eNodeB. The eNodeB selects, according to a network topology, anMME to serve the UE, and forwards the access request message of the UEto the MME for processing. The MME selected by the eNodeB according tothe network topology is the first MME.

The access request message may be an attach request or a routing areaupdate request.

If a type of the access request message is an attach request message,the identity information of the UE is an international mobile subscriberidentity (IMSI for short) of the UE.

The attach request message further includes: a core network capabilityof the UE, a discontinuous reception parameter specified by the UE, anencryption option transmission mark, an attach type, a NAS sequencenumber, NAS-media access control, and the like.

If the access request message is a routing area update request message,the identity information of the UE is an IMSI of the UE; or the identityinformation of the UE may be further a globally unique temporaryidentity (GUTI for short) that is allocated, to the UE, by an MME thatexecutes a previous attach procedure of the UE or an MME that is in aprevious routing area update procedure before the current routing areaupdate request.

The routing area update request message further includes an attach typeand other information.

802: Determine, according to the identity information of the UE, a typeof an MME that the UE needs to access.

Optionally, the first MME may determine, according to the identityinformation of the UE and preconfiguration indication information, thetype of the MME that the UE needs to access, where the preconfigurationindication information includes information about a correspondencebetween the identity information of the UE and the type of the MME thatthe UE needs to access.

The preconfiguration indication information is stored in the MME, andincludes information about the correspondence between identity (ID forshort) information of the UE and the type of the MME that the UE needsto access.

Specifically, the identity information of the UE included in thepreconfiguration indication information is specifically informationabout an ID of the UE.

Further, the first MME may search, according to the IMSI of the UE, forthe ID of the corresponding UE and the information about the type of theMME that the UE needs to access, and determine the type of the MME thatthe UE needs to access.

Optionally, the first MME may further obtain subscription data of the UEfrom a home subscriber server HSS according to the identity informationof the UE, where the subscription data includes information about thetype of the MME that the UE needs to access.

The subscription data is stored in the HSS, and includes informationabout a correspondence between an ID of the UE and the type of the MMEthat the UE needs to access.

Specifically, the identity information of the UE included in thesubscription data of the UE is specifically information about the ID ofthe UE.

Further, the first MME may request and obtain, from the HSS according tothe IMSI of the UE, the ID of the corresponding UE and the informationabout the type of the MME that the UE needs to access in thesubscription data, and determine the type of the MME that the UE needsto access.

Optionally, if the UE initiates a routing area update request, the firstMME may further obtain, according to the identity information of the UE,a mobility management context of the UE from an original MME accessed bythe UE, where the mobility management context includes the informationabout the type of the MME that the UE needs to access.

The mobility management context is stored in the original MME, andincludes a GUTI allocated to the UE by an MME that executes a previousattach procedure of the UE or an MME that is in a previous routing areaupdate procedure before the current routing area update request, anindication of the type of the MME that the UE needs to access, a TAIthat is effectively accessed by the UE last time, a core networkcapability of the UE, a discontinuous reception parameter specified bythe UE, a type of a packet data network, security encryption information(for example, an encryption and decryption manner for interaction withthe UE), an attach type, a NAS sequence number, NAS-media accesscontrol, and the like.

Specifically, the identity information of the UE included in themobility management context is specifically the GUTI of the UE.

Further, the first MME learns, according to the GUTI of the UE, anidentifier of the original MME storing the mobility management contextof the UE, and requests the original MME to forward mobility managementcontext information of the UE, and the first MME determines, accordingto the indication, which is included in the mobility management contextinformation, of the type of the MME that the UE needs to access, thetype of the MME that the UE needs to access.

It should be noted that because an operator usually distinguishesservice types of UEs according to number segments or package types ofthe UEs, types of MMEs may be classified according to the numbersegments of the UEs, or may be classified according to the package typesof the UEs, or may be classified according to an actual requirement ofthe operator. How to classify the types of the MMEs is not specificallylimited in the present invention.

803: Reselect a second MME according to the type of the MME that the UEneeds to access.

Specifically, if the type of the MME that the UE needs to access isinconsistent with a type of the first MME, the first MME may reselect asecond MME according to the type of the MME that the UE needs to access;an address of a type of the second MME is obtained according topreconfigured information about types of all MMEs on a network or isobtained from a DNS server, and the first MME establishes a connectionrelationship with the second MME according to the address, implementingreselection of an MME for the UE.

It should be noted that if the type of the MME that needs to be accessedincludes multiple MMEs that can be used, a connection is established toa closest MME that is selected according to a network topology.

804: Forward the access request message to the second MME, so that thesecond MME executes an access request procedure of the UE.

Specifically, the first MME forwards the already received access requestmessage of the UE to the second MME, so that the second MME may executethe access request procedure of the UE.

It should be noted that, persons skilled in the art may understand that,if the type of the MME that the UE needs to access is consistent withthe type of the first MME, an MME does not need to be reselected, andthe first MME directly executes and completes the access requestprocedure of the UE. This case is not in the scope of the description ofthe present invention.

This embodiment of the present invention provides an MME reselectionmethod. Based on the foregoing technical solution, a first MME mayreselect, for UE, an MME that the UE needs to access, that is, a secondMME, and forward an access request message of the UE to the second MME,so that the UE can use a correct MME in time to execute an accessrequest procedure. Meanwhile, because the first MME may select, for theUE, an MME matching a type of a service of the UE, which is equivalentto enabling UE that subscribes to a different service to access an MMEcorresponding to the type of the service of the UE, so that an operatormay use MMEs to classify UEs that are managed, thereby improvingmanagement efficiency of the operator. Further, an MME in the prior artcan execute the access request procedure according to only an accessrequest message of the UE forwarded by an eNodeB, while the first MME inthis solution may further help the UE to select an MME that the UE needsto access and forward an access request of the UE. Therefore, duringimplementation of this solution, only software of an existing MME needsto be updated, to achieve an objective that the MME can help the UE toperform reselection and forward an access request to an MME that needsto be accessed. In addition, because a quantity of MMEs is relativelysmall, impact on an operator network is also relatively small.

Based on the second MME provided in the foregoing embodiment, anembodiment of the present invention provides another MME reselectionmethod. The method is executed by the second MME. The second MME is anMME that is reselected by the first MME for UE according to a type of anMME that the UE needs to access. As shown in FIG. 9, the methodincludes:

901: Receive an access request message that is sent by user equipment UEand that is forwarded by a first MME, where the access request messageincludes an identity of the UE.

The first MME is an MME that is selected by an eNodeB for the UEaccording to a network topology.

Specifically, the second MME receives the access request message that issent by the UE and that is forwarded by the first MME.

For a detailed description of the access request message, refer to thedescription of 801, and details are not described herein in thisembodiment again.

902: Execute an access request procedure of the UE according to theaccess request message.

Optionally, when the access request procedure of the UE is executedaccording to the access request message, the second MME may send aninteraction message to the UE by using the first MME, and receive, byusing the first MME, the interaction message sent by the UE.

It should be noted that, persons skilled in the art may understand that,when executing the access request procedure of the UE, the second MMEmay send the interaction message to the UE by using the first MME, andreceive, by using the first MME, the interaction message sent by the UE;or as shown in FIG. 2 and FIG. 3 in the prior art, the second MME maydirectly send the interaction message to the UE by using the eNodeB, andreceive, by using the eNodeB, the interaction message sent by the UE, asshown in steps 205 to 216 and steps 306 to 315; or any other device ormanner that may help the second MME to forward the interaction messageto the UE is used, which is not specifically limited in the presentinvention. For ease of description of the present invention, theforegoing embodiment is described by using only an example in which thesecond MME sends the interaction message to the UE by using the firstMME and the first MME receives, by using the first MME, the interactionmessage sent by the UE.

This embodiment of the present invention provides an MME reselectionmethod. Based on the foregoing technical solution, a second MME mayexecute an access request procedure of UE according to an access requestmessage of the UE forwarded by a first MME, so that the UE can use acorrect MME in time to execute the access request procedure. Meanwhile,an MME in the prior art can execute the access request procedureaccording to only an access request message of the UE forwarded by aneNodeB, and the second MME in this solution may further execute theaccess request procedure of the UE according to the access requestmessage forwarded by the first MME. Therefore, during implementation ofthis solution, only software of an existing MME needs to be updated, toachieve an objective that the MME may execute the access requestprocedure of the UE according to the access request message forwarded bythe first MME. In addition, because a quantity of MMEs is relativelysmall, impact on an operator network is also relatively small.

An example in which UE executes an attach procedure is used below todescribe in detail an MME reselection method provided in the presentinvention, and a specific implementation process is shown in FIG. 10.

It should be noted that an interaction process of the attach procedurediscussed in this embodiment is the same as some steps of an existingattach procedure, the same steps are not described one by one, and onlyan interaction process of MME reselection provided in this embodiment ofthe present invention is emphasized and described.

1001: UE sends an attach request message to an eNodeB.

1002: The eNodeB forwards, to a first MME, the attach request messagesent by the UE.

1003 a: The first MME and an HSS authenticate the UE.

1003 b: The first MME and the UE perform security setting on a NASmessage.

1004: The first MME exchanges a location update request message andacknowledges a location update request acknowledgement message with theHSS.

100A: Reselect an MME for the UE according to a type of an MME that theUE needs to access.

Specifically, the first MME determines, according to identityinformation of the UE, the type of the mobility management entity MMEthat the UE needs to access, reselects the MME, that is, a second MME,and establishes a connection to the second MME. For a specific process,refer to the descriptions of 802 and 803.

It should be noted that, if the UE does not need to reselect the MME,the first MME directly executes and completes a subsequent attachprocedure of the UE, and it is unnecessary to use the second MME toexecute the attach procedure. This case is not in the scope of thedescription of the present invention.

100B: The first MME forwards a context to a second MME.

The context includes the attach request message sent by the UE.

1005: The second MME sends a create session request message to an S-GW.

1006: The S-GW connects to and sends the create session request messageto a P-GW.

1007: The P-GW returns a create session response message to the S-GW.

1008: The S-GW returns the create session response message to the secondMME.

100C: The second MME exchanges a location update request message and alocation update request acknowledgement message with the HSS.

Specifically, the second MME sends the location update request messageto the HSS, and the HSS updates stored information about a location ofan MME on which the UE is located, where the HSS updates informationabout a location at which the UE is served by the first MME toinformation about a location at which the UE is served by the secondMME. After updating the information about the location of the MME onwhich the UE is located, the HSS returns the location update requestacknowledgement message to the second MME.

100D: The HSS exchanges a location deletion request message and alocation deletion request acknowledgement message with the first MME.

Specifically, the HSS initiates the location deletion request message tothe first MME; the first MME deletes the stored location information ofthe UE, that is, a mobility context established between the first MMEand the UE, and returns the location deletion request acknowledgementmessage to the HSS after the deletion.

100E: The second MME sends a context to the first MME.

The context includes an attach accept message and an initial contextsetup request message.

1009: The first MME sends an initial context setup request message theeNodeB.

1010: The eNodeB sends a radio resource control protocol connectionreconfiguration message to the UE.

1011: The UE sends a radio resource control protocol connectionreconfiguration complete message to the eNodeB.

1012: The eNodeB sends an initial context setup response message thefirst MME.

100F: The first MME forwards the context to the second MME.

The context includes an initial context setup response, and the initialcontext setup response message includes a TEID allocated by the eNodeBto a user plane, a user plane address of the eNodeB, and the like.

1013: The UE sends a direct transmission message to the eNodeB.

1014: The eNodeB forwards an attach complete message to the first MME.

100G: The first MME forwards a context to the second MME.

The context includes the attach complete message.

1015: The second MME sends a bearer update request message to the S-GW.

1016: The S-GW sends a bearer update response message to the second MME,and starts to send, to the eNodeB, a downlink data packet that isbuffered starting from 1007.

Based on the foregoing embodiment, a first MME may reselect, for UE, anMME that the UE needs to access, that is, a second MME, and forward anaccess request message of the UE to the second MME, and the second MMEmay execute an access request procedure of the UE according to theaccess request message of the UE forwarded by the first MME, so that theUE can use a correct MME in time to execute the access requestprocedure.

An example in which UE executes an attach procedure is used below todescribe in detail an MME reselection method provided in the presentinvention, and a specific implementation process is shown in FIG. 11.

It should be noted that an interaction process of the attach procedurediscussed in this embodiment is the same as some steps of the attachprocedure of the MME reselection provided in the previous embodiment,the same steps are not described one by one again, and only anencryption process when an MME interacts with UE is emphasized anddescribed.

It should be further noted that, all steps indicated by using dashedboxes in FIG. 11 represent optional steps.

1101: UE sends an attach request message to an eNodeB.

1102: The eNodeB forwards, to a first MME, the attach request messagesent by the UE.

1103 a: The first MME and an HSS authenticate the UE.

1103 b: The first MME and the UE perform security setting on a NASmessage.

1104: The first MME exchanges a location update request message and alocation update request acknowledgement message with the HSS.

110A: Reselect an MME for the UE according to a type of an MME that theUE needs to access.

110B: The first MME forwards a context to a second MME.

The context includes the attach request message sent by the UE.

Optionally, the context may further include a security context (that is,an encryption manner agreed between the MME and the UE, key information,and the like) established by the first MME and the UE.

1105: The second MME sends a create session request message to an S-GW.

1106: The S-GW connects to and sends the create session request messageto a P-GW.

1107: The P-GW returns a create session response message to the S-GW.

1108: The S-GW returns the create session response message to the secondMME.

110C: The second MME exchanges a location update request message and alocation update request acknowledgement message with the HSS.

110D: The HSS exchanges a location deletion request message and alocation deletion request acknowledgement message with the first MME.

110 a 1: The second MME encrypts a context.

The context is a context that is to be sent by the second MME to thefirst MME, and includes an attach accept message and an initial contextsetup request message.

Specifically, whether this step exists depends on 110B.

If the context in 110B includes the security context established by thefirst MME and the UE, in this step, the second MME needs to encrypt thecontext in the encryption manner in the security context that isestablished by the first MME and the UE and that is forwarded by thefirst MME in 110B.

If the context in 110B does not include the security context establishedby the first MME and the UE, this step is omitted, and the second MMEdoes not need to perform an encryption operation.

110E: The second MME sends the context to the first MME.

The context includes an attach accept message and an initial contextsetup request message.

110 a 2: The first MME encrypts the context.

The context is a context sent by the second MME, and includes the attachaccept message and the initial context setup request message.

Specifically, whether this step exists depends on 110B.

If the context in 110B includes the security context established by thefirst MME and the UE, this step is omitted, and the first MME does notneed to perform an encryption operation.

If the context in 110B does not include the security context establishedby the first MME and the UE, because the first MME does not forward thesecurity context established by the first MME and the UE to the secondMME, the second MME cannot learn an encryption and decryption manner forinteraction with the UE, and the first MME needs to encrypt the contextsent by the second MME.

1109: The first MME sends an initial context setup request message theeNodeB.

1110: The eNodeB sends a radio resource control protocol connectionreconfiguration message to the UE.

1111: The UE sends a radio resource control protocol connectionreconfiguration complete message to the eNodeB.

1112: The eNodeB sends an initial context setup response message thefirst MME.

110 b 2: The first MME decrypts the initial context setup responsemessage.

The initial context setup response message is sent by the eNodeB.

Specifically, whether this step exists depends on 110B.

If the context in 110B includes the security context established by thefirst MME and the UE, this step is omitted, and the first MME does notneed to perform a decryption operation.

If the context in 110B does not include the security context establishedby the first MME and the UE, because the first MME does not forward thesecurity context established by the first MME and the UE to the secondMME, the second MME cannot learn an encryption and decryption manner forinteraction with the UE, and the first MME needs to decrypt the initialcontext setup response message that is to be sent to the second MME.

110F: The first MME forwards a context to the second MME.

The context includes the initial context setup response message.

110 b 1: The second MME decrypts the context.

The context is a context sent by the first MME, and includes the initialcontext setup response message.

Specifically, whether this step exists depends on 110B.

If the context in 110B includes the security context established by thefirst MME and the UE, in this step, the second MME needs to decrypt, inthe decryption manner in the security context that is established by thefirst MME and the UE and that is forwarded by the first MME in 110B, theinitial context setup response message forwarded by the first MME.

If the context in 110B does not include the security context establishedby the first MME and the UE, this step is omitted, and the second MMEdoes not need to perform a decryption operation.

1113: The UE sends a direct transmission message to the eNodeB.

1114: The eNodeB forwards an attach complete message to the first MME.

110 c 2: The first MME decrypts the attach complete message.

The attach complete message is sent by the eNodeB.

Specifically, whether this step exists depends on 110B.

If the context in 110B includes the security context established by thefirst MME and the UE, this step is omitted, and the first MME does notneed to perform a decryption operation.

If the context in 110B does not include the security context establishedby the first MME and the UE, because the first MME does not forward thesecurity context established by the first MME and the UE to the secondMME, the second MME cannot learn an encryption and decryption manner forinteraction with the UE, and the first MME needs to decrypt the attachcomplete message that is to be sent to the second MME.

110G: The first MME forwards a context to the second MME.

The context includes the attach complete message.

110 c 1: The second MME decrypts the context.

The context is a context sent by the first MME, and includes the attachcomplete message.

Specifically, whether this step exists depends on 110B.

If the context in 110B includes the security context established by thefirst MME and the UE, in this step, the second MME needs to decrypt, inthe decryption manner in the security context that is established by thefirst MME and the UE and that is forwarded by the first MME in 110B, theattach complete message forwarded by the first MME.

If the context in 110B does not include the security context establishedby the first MME and the UE, this step is omitted, and the second MMEdoes not need to perform a decryption operation.

1115: The second MME sends a bearer update request message to the S-GW.

1116: The S-GW sends a bearer update response message to the second MME,and starts to send, to the eNodeB, a downlink data packet that isbuffered starting from 1107.

Based on the foregoing embodiment, a first MME may reselect, for UE, anMME that the UE needs to access, that is, a second MME, and forward anaccess request message of the UE to the second MME, and the second MMEmay execute an access request procedure of the UE according to theaccess request message of the UE forwarded by the first MME, so that theUE can use a correct MME in time to execute the access requestprocedure.

An example in which UE executes a routing area update procedure is usedbelow to describe in detail an MME reselection method provided in thepresent invention, and a specific implementation process is shown inFIG. 12.

It should be noted that an interaction process of the routing areaupdate procedure discussed in this embodiment is the same as some stepsof an existing routing area update procedure, the same steps are notdescribed one by one, and only an interaction process of MME reselectionprovided in this embodiment of the present invention is emphasized anddescribed.

It should be further noted that, all steps indicated by using dashedboxes in FIG. 12 represent optional steps.

1201: UE sends a routing area update request message to an eNodeB.

1202: The eNodeB forwards the routing area update request message to afirst MME.

1203: The first MME sends a mobility management context request messageto an original MME.

1204: The original MME returns a mobility management context responsemessage to the first MME.

1205 a: The first MME and an HSS authenticate the UE.

1205 b: The first MME and the UE perform security setting on a NASmessage.

It should be noted that whether this step exists depends on 1204.

If a mobility management context that is returned by the original MME tothe first MME in 1204 includes a security context of the original MMEand the UE, this step is omitted, and the first MME and the UE do notneed to perform security setting on the NAS message.

If a mobility management context that is returned by the original MME tothe first MME in 1204 does not include a security context of theoriginal MME and the UE, the first MME and the UE need to performsecurity setting on the NAS message in this step.

120A: Reselect an MME for the UE according to a type of an MME that theUE needs to access.

Specifically, the first MME determines, according to identityinformation of the UE, the type of the mobility management entity MMEthat the UE needs to access, reselects the MME, that is, a second MME,and establishes a connection to the second MME. For a specific process,refer to the descriptions of 802 and 803.

It should be noted that, if the UE does not need to reselect the MME,the first MME directly executes and completes a subsequent routing areaupdate procedure of the UE, and it is unnecessary to use the second MMEto perform the routing area update procedure. This case is not in scopeof the description of the present invention.

120B: The first MME forwards a context to the second MME.

The context includes the routing area update request message sent by theUE and a mobility management context, which is obtained by the firstMME, of the UE.

Optionally, the context may further include a security context (that is,an encryption manner agreed between the first MME and the UE, keyinformation, and the like) established by the first MME and the UE.

1207: The second MME initiates a bearer update request message to anS-GW.

1208: The S-GW sends the bearer update request message to a P-GW.

1209: The P-GW returns a bearer update response message to the S-GW.

1210: The S-GW sends the bearer update response message to the secondMME.

1211: The second MME initiates a location update request message to anHSS.

1212: The HSS exchanges a location deletion request message and alocation deletion request acknowledgement message with the original MME.

1213: The HSS returns a location update request acknowledgement messageto the second MME.

120C1: The second MME encrypts a routing area update accept message.

The routing area update accept message includes a GUTI that is allocatedby the second MME to the UE.

Specifically, whether this step exists depends on 120B.

If the context in 120B includes the security context established by thefirst MME and the UE, in this step, the second MME needs to encrypt therouting area update accept message in the encryption manner in thesecurity context that is established by the first MME and the UE andthat is forwarded by the first MME in 120B.

If the context in 120B does not include the security context establishedby the first MME and the UE, this step is omitted, and the second MMEdoes not need to perform an encryption operation.

120D: The second MME sends a context to the first MME.

The context includes the routing area update accept message and an S-GWchange indication.

1206: The first MME sends a context acknowledgement message to theoriginal MME.

The context acknowledgement message includes the S-GW change indication.

It should be noted that, because selection of the S-GW in the routingarea update procedure is performed by the second MME, the first MME cansend the context acknowledgement to the original MME only after thesecond MME returns an S-GW change indication message. Therefore, 1206 isperformed herein.

120C2: The first MME encrypts the routing area update accept message.

The routing area update accept message is included in the context sentby the second MME.

Specifically, whether this step exists depends on 120B.

If the context in 120B includes the security context established by thefirst MME and the UE, this step is omitted, and the first MME does notneed to perform an encryption operation.

If the context in 120B does not include the security context establishedby the first MME and the UE, because the first MME does not forward thesecurity context established by the first MME and the UE to the secondMME, the second MME cannot learn an encryption and decryption manner forinteraction with the UE, and the first MME needs to encrypt the routingarea update accept message sent by the second MME.

1214: The first MME sends the routing area update accept message to theeNodeB.

The routing area update accept message includes the GUTI that isallocated by the second MME to the UE.

1215: The eNodeB forwards the routing area update accept message to theUE.

Based on the foregoing embodiment, a first MME may reselect, for UE, anMME that the UE needs to access, that is, a second MME, and forward anaccess request message of the UE to the second MME, and the second MMEmay execute an access request procedure of the UE according to theaccess request message of the UE forwarded by the first MME, so that theUE can use a correct MME in time to execute the access requestprocedure.

An example in which UE executes a routing area update procedure is usedbelow to describe in detail an MME reselection method provided in thepresent invention, and a specific implementation process is shown inFIG. 13.

It should be noted that, an interaction process of the routing areaupdate procedure discussed in this embodiment is the same as some stepsof the routing area update procedure of MME reselection provided in theprevious embodiment, and the same steps are not described one by oneherein again. A difference lies in a channel by using which the secondMME obtains a mobility management context of the UE. In the previousembodiment, the mobility management context of the UE that the secondMME obtains is first obtained by the first MME from the original MME andthen forwarded to the second MME. In this embodiment, the mobilitymanagement context of the UE obtained by the second MME is directlyrequested and obtained by the second MME from the original MME.Therefore, this embodiment emphasizes and describes only this process.

1301: UE sends a routing area update request message to an eNodeB.

1302: The eNodeB forwards the routing area update request message to afirst MME.

1303: The first MME sends a mobility management context request messageto an original MME.

1304: The original MME returns a mobility management context responsemessage to the first MME.

130A: Reselect an MME for the UE according to a type of an MME that theUE needs to access.

Specifically, the first MME determines, according to identityinformation of the UE, the type of the mobility management entity MMEthat the UE needs to access, reselects the MME, that is, the second MME,and establishes a connection to the second MME. For a specific process,refer to the descriptions of 802 and 803.

It should be noted that, if the UE does not need to reselect the MME,the first MME directly executes and completes a subsequent routing areaupdate procedure of the UE, and it is unnecessary to use the second MMEto execute the routing area update procedure. This case is not in thescope of the description of the present invention.

130B: The first MME forwards a context to a second MME.

The context includes the routing area update request message sent by theUE.

130C: The second MME sends the mobility management context requestmessage to the original MME.

Specifically, the second MME learns, according to information about aGUMMEI included in a GUTI, an address of the original MME at which amobility management context of the UE is located, and sends the mobilitymanagement context request message to the original MME.

The mobility management context request message includes the GUTI of theUE.

130D: The original MME returns the mobility management context responsemessage to the second MME.

Specifically, the original MME determines a mobility management contextof the UE according to the GUTI, and returns the mobility managementcontext of the UE to the second MME according to the mobility managementcontext response message.

1305 a: The second MME and an HSS authenticate the UE.

1305 b: The second MME and the UE perform security setting on a NASmessage.

Specifically, the second MME and the UE perform security setting, suchas integrity protection, an encryption manner, or key information, onthe NAS message.

It should be noted that whether this step exists depends on 130D.

If a mobility management context that is returned by the original MME tothe second MME in 130D includes a security context of the original MMEand the UE, this step is omitted, and the second MME and the UE do notneed to perform security setting on the NAS message.

If a mobility management context that is returned by the original MME tothe second MME in 130D does not include a security context of theoriginal MME and the UE, the second MME and the UE need to performsecurity setting on the NAS message in this step.

1306: The second MME sends a context acknowledgement message to theoriginal MME.

The context acknowledgement message includes an S-GW change indication.

1307: The second MME initiates a bearer update request message to anS-GW.

1308: The S-GW sends a bearer update request message to a P-GW.

1309: The P-GW returns a bearer update response message to the S-GW.

1310: The S-GW sends the bearer update response message to the secondMME.

1311: The second MME initiates a location update request message to theHSS.

1312: The HSS exchanges a location deletion request message and alocation deletion request acknowledgement message with the original MME.

1313: The HSS returns a location update request acknowledgement messageto the second MME.

130E: The second MME sends a context to the first MME.

The context includes a routing area update accept message, and therouting area update accept message includes the GUTI that is allocatedby the second MME to the UE.

1314: The MME sends the routing area update accept message to theeNodeB.

The routing area update accept message includes the GUTI that isallocated by the second MME to the UE.

1315: The eNodeB forwards the routing area update accept message to theUE.

Based on the foregoing embodiment, a first MME may reselect, for UE, anMME that the UE needs to access, that is, a second MME, and forward anaccess request message of the UE to the second MME, and the second MMEmay execute an access request procedure of the UE according to theaccess request message of the UE forwarded by the first MME, so that theUE can use a correct MME in time to execute the access requestprocedure.

In the several embodiments provided in the present application, itshould be understood that the disclosed MME and method may beimplemented in other manners. For example, the described MME embodimentis merely exemplary. For example, the unit division is merely logicalfunction division and may be other division in actual implementation.For example, a plurality of units or components may be combined orintegrated into another system, or some features may be ignored or notperformed. In addition, the displayed or discussed mutual couplings ordirect couplings or communication connections may be implemented byusing some interfaces. The indirect couplings or communicationconnections between the apparatuses or units may be implemented inelectronic or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected according toactual needs to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of the presentinvention may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit. The integrated unit may be implemented in a form ofhardware, or may be implemented in a form of hardware in addition to asoftware functional unit.

When the foregoing integrated unit is implemented in a form of asoftware functional unit, the integrated unit may be stored in acomputer-readable storage medium. The software functional unit is storedin a storage medium and includes several instructions for instructing acomputer device (which may be a personal computer, a server, or anetwork device) to perform some of the steps of the methods described inthe embodiments of the present invention. The foregoing storage mediumincludes: any medium that can store program code, such as a USB flashdrive, a removable hard disk, a read-only memory (ROM for short), arandom access memory (RAM for short), a magnetic disk, or an opticaldisc.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the present inventionbut not for limiting the present invention. Although the presentinvention is described in detail with reference to the foregoingembodiments, persons of ordinary skill in the art should understand thatthey may still make modifications to the technical solutions describedin the foregoing embodiments or make equivalent replacements to sometechnical features thereof, without departing from the scope of thetechnical solutions of the embodiments of the present invention.

The foregoing descriptions are merely specific implementation manners ofthe present invention, but are not intended to limit the protectionscope of the present invention. Any variation or replacement readilyfigured out by persons skilled in the art within the technical scopedisclosed in the present invention shall fall within the protectionscope of the present invention. Therefore, the protection scope of thepresent invention shall be subject to the protection scope of theclaims.

What is claimed is:
 1. A first mobility management apparatus, comprising: a receiver, configured to receive an access request message sent by user equipment UE, wherein the access request message carries identity information of the UE; a processor, configured to: determine, according to the identity information of the UE, a type of a mobility management apparatus that the UE needs to access; and reselect a second mobility management apparatus according to the type of the mobility management apparatus that the UE needs to access; and a transmitter, configured to forward the access request message to the second mobility management apparatus, wherein the access request message is for requesting the second mobility management apparatus to execute an access request procedure of the UE; wherein the processor is configured to: obtain, according to the identity information of the UE, mobility management context information of the UE from an original mobility management apparatus accessed by the UE, wherein the mobility management context information comprises information about the type of the mobility management apparatus that the UE needs to access; and determine, according to the mobility management context information, the type of the mobility management apparatus that the UE needs to access.
 2. The first mobility management apparatus according to claim 1, wherein the transmitter is configured to forward the access request message and the mobility management context information of the UE to the second mobility management apparatus, so that the second mobility management apparatus executes the access request procedure of the UE according to the access request message and the mobility management context information of the UE.
 3. A mobility management apparatus reselection method, wherein the method comprises: receiving an access request message sent by user equipment (UE), wherein the access request message carries identity information of the UE; determining, according to the identity information of the UE, a type of a mobility management apparatus that the UE needs to access; reselecting a second mobility management apparatus according to the type of the mobility management apparatus that the UE needs to access; and forwarding the access request message to the second mobility management apparatus, wherein the access request message is for requesting the second mobility management apparatus to execute an access request procedure of the UE; wherein the determining the type of the mobility management apparatus that the UE needs to access comprises: obtaining, according to the identity information of the UE, mobility management context information of the UE from an original mobility management apparatus accessed by the UE, wherein the mobility management context information comprises information about the type of the mobility management apparatus that the UE needs to access; and determining, according to the mobility management context information, the type of the mobility management apparatus that the UE needs to access.
 4. The method according to claim 3, wherein after the forwarding the access request message to the second mobility management apparatus, the method further comprises: forwarding the mobility management context information of the UE to the second mobility management apparatus.
 5. A non-transitory computer-readable storage medium storing a program to be executed by a processor, the program including instructions to configure the processor for: receiving an access request message sent from user equipment (UE), wherein the access request message carries identity information of the UE; determining, according to the identity information of the UE, a type of a mobility management apparatus that the UE needs to access; reselecting a second mobility management apparatus according to the type of the mobility management apparatus that the UE needs to access; and forwarding the access request message to the second mobility management apparatus, wherein the access request message is for requesting the second mobility management apparatus to execute an access request procedure of the UE; wherein the determining the type of the mobility management apparatus that the UE needs to access comprises: obtaining, according to the identity information of the UE, mobility management context information of the UE from an original mobility management apparatus accessed by the UE, wherein the mobility management context information comprises information about the type of the mobility management apparatus that the UE needs to access; and determining, according to the mobility management context information, the type of the mobility management apparatus that the UE needs to access.
 6. The non-transitory computer-readable storage medium to claim 5, wherein the program further includes instructions to configure the processor for: forwarding the mobility management context information of the UE to the second mobility management apparatus. 